Portable sanding machine



Jan. 15, 1952 B, K R g-f 2,582,470

PORTABLE SANDING MACHINE Filed Nov. 2, 1949 4 Sheets-Sheet l INVENTOR.

H/IRRY J R/DDLE BY flLL/M/ 5. W/iL/(EA Jan. 15, 1952 A. B. WALKER ETAL 2,582,470

PORTABLE SANDING MACHINE F iled Nov. 2, 1949 4 Sheets-Sheet 2 JNVENTOR. Hme/ev J R/DDLE HAL/W B. M/flLK/El? Jan. 15, 1952 ER ETAL 2,582,470

I PQRTABLE SANDING MACHINE Filed Nov. 2, 1949 4 sheet -sneet s m r w I I 1 T L n i I I I 1 T" 4L I I H L W 4 I a T *s 26 4a 42 r v Patented Jan. 15, 1952 PORTABLE. SANDING MACHINE Allan B. Walker, Piedmont, and Harry J. Riddle, Alameda, Calif.; said Walker assignor to said Riddle Application November 2, 1949, Serial No. 124,958 1 Claim. (01. 51-170) The invention relates to sanding machines of the portable, power-driven type, utilizing one or more reciprocally driven sanding shoes and adapted for sanding or other finishing operations on furniture, floors, woodwork, or the like.

An object of the present invention is to provide in a portable sanding or finishing device of the character described a powerful, ruggedly constructed, high-speed machine, having an improved, symmetrically-balanced arrangement and construction of the parts making up the drive assembly, permitting the use and application of greater power for the size of the unit-and with large factors of safety in the design afiording heavy duty and long-continued operation of the machine.

Another object of the invention is to provide a machine of the character described having a pair of reciprocating sanding shoes driven in an outof-phase, opposed and balanced relation, thereby permitting the machine to be easily handled and precisely manipulated over the work to be sanded, with minimum effort.

A further object of the invention is to provide a sanding machine of the character described-embodying an improved universal support for the sanding shoes, thus enabling the sanding or finishing of work having other than a flat surface and at the same time effectively preventing any tendency of the leading edges of the shoes to tip or bite into the surface being worked.

Still another object of the invention is to provide a sanding machine of the character above, having an improved sanding pattern permitting the sanding or finishing operation tobe carried I into corners and to the wall edges of fioors and the like. i

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following descrip-- tion of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claim.

' Refering to said drawings:

Figure 1 is a side elevation, shown partly in cross section, of a sanding machine constructed in accordance with the present invention.

Figure 2 is a plan sectional view taken substantially on the plane of line 2--2 of Figure 1.

Figure 3 is a plan sectional view taken substantially on the plane of line 3-3 of Figure 1 andv shown on a somewhat enlarged scale.

Figure 4 is an end elevation of the machine with a portion shown in cross section, taken on the plane of line 44 of Figure 1, the scale being slightly enlarged with respect to Figure 1.

Figure 5 is across-sectional view of the machine on the same scale as Figure 4 and taken substantially on the plane of line 55 of Figure 1.

Figure 6 is a further enlarged sectional view taken substantially on the plane of line 6-6 of Figure 3. V,

Figure '7 is a cross-sectional view taken substantially on the plane of line 1-1 of Figure 6.

Figure 8 is a cross-sectional view taken substantially on the plane of line 8-8 of Figure 6.

The sanding machine of the present invention and as depicted in the accompanying drawing consists in an integral assembly including an electric motor II, a casing 12 for the drive assembly, and a pair of shoes 13 and I4 mounted in underlying relation to the casing l2 and supported and driven for reciprocation. The casing I2 is here provided with top wall l6 and depending side walls I! and I 8, and end walls 19 and 2|, forming a continuous depending skirt around the top wall I 6. The casing is preferably of substantially rectangular form as viewed in plan, see Figure 2, and the front and rear ends of the easing may be rounded for appearance as illustrated in Figure 1. A gear housing 22 is secured within the casing to the under side of the top wall I 6 and as here shown projects up through a central opening provided in the top wall for securing thereat to a cover plate 23, the latter preferably overlying the periphery of the opening in the top wall so as to clamp the top wall, as shown in Figures 1 and 4, between a depending flange 24 on the cover and an annular shoulder 26 on the gear housing. The electric motor II is set in a vertical operating position and the lower end of the motor case is preferably recessed to fit around and upon the periphery of the cover plate 23 and upon the upper side of the casing l 2. The motor casing and gear housing assembly is here unitarily secured together by means of through bolts 21 and 28, which extend from the under side of the gear housing, through the gear housing and cover plate 23, and up through the length of the motor housing through the motor stator 29, and

are threadably attached at their upper ends in end portions 3| and 32 of handles 33 and 34. As will be noted from Figure 1, handles 33 and 34 are positioned vertically on opposite sides of the motor and are attached at their lower ends to the opposite end walls I9 and 2| of the casing and curved inwardly at the upper ends 3| and 32 for insertion through opposed openings in the motor housing for attachment to the upper ends of the through bolts 21 and 28. Preferably, additional bolts 39 are used for fastening the cover plate 23 to the gear housing and thereby securely clamping the gear housing to the casing l2.

As an important feature of the above described construction, the cover plate 23 for the gear housing also forms a lower end wall for the electric motor and is desirably fitted with a bearing 36 for journalling the lower end 31 of the motor shaft 38, the shaft end 31, as here shown, projecting through the bearing 36 and into a gear chamber 39 provided in the housing 22. Preferably, a conventional air propelling fan 4| is secured on the motor shaft 38 between the bearing 36 and the rotor 42 of the electric motor, air circulation being provided through the motor between air slots 43 (see Figure 4) and 44 (see Figure 1). As will be noted from Figure l, the handles 33 and 34 are spaced from the motor housing to permit easy gripping in the hands of the user, and an electric switch 45 may be attached to one of the handles as here shown for convenient turning on and off of the electric motor.

The gear chamber 39, above noted, here opens to the top of the housing 22-and is closed oif and sealed from the motor by the cover plate 23. The chamber has a sufficient width an'ddepth to accommodate a centrally arranged worm gear 41 secured on the shaft end 31, andworm pinions 48 and 49 enmeshed therewith and positioned on opposite sides of the wormgear 41, the pinions 48 and 49 being mounted on driven shafts and 52 for rotation about horizontal axes and with the gears mounted in a substantially common vertical plane extending transversely across the gear housing. With reference to Figure 2, it will be noted that the driven shafts 5| and 52 are journalled in the gear housing-22 for rotation about transversely spaced parallel horizontal axes on opposite sides of and extending perpendicular to the drive shaft 31. Shaft 52 is journalled in bearings 53 and 54 mounted in the opposite sides of the gear housing, and projects from the outer side of the gear housing and into the interior'of casing |2 adjacentend wall 2 I, and has afiixed to its outer end portion 56, for rotation therewith, a cam 51. In asimilar manner, shaft 5| is journalled in bearings 58 and 59 in the opposite sides of the gear housing and projects from the gear housing into the interior of casing l2 adjacent end l9, where the outer projecting shaft end 6| is fitted with a cam 62. With further reference to Figures 2, 4 and 5, it will be noted that worm pinions 48 and 49 are splined to their respective shafts 5| and 52 and cams 51 and 62 are keyed to their respective shaft ends 56 and 6|. If desired and as here shown, thepinions 48 and 49 maybe held in central position within the chamber 39 and in proper engagement with the worm gear 41, by sleeves 63, 64, 66 and 61 mounted on shafts 5| and 52 on opposite sides of pinions 48 and 49 and extending into abutting relation with the adjacent shaft bearings.

A pair of slide members 13 and 14 are connected to the cams 51 and'62 by cam followers 16 and 11 and are, in turn, connected to the shoes l3 and I4, so that the rotary motion of the driven shafts 5| and 52 as translated by the cams into a horizontal reciprocating motion is transmitted to, the slide members and the shoes. The preferred construction of the slide members and shoe connection is best illustrated in Figure 5. With reference to this gure it will be noted that there are positioned along the length of casing |2 on the opposite side walls l1 and |8 a pair of elongated guide ways 18 and 19 which slidably support for reciprocation the slide members 13 and 14. The guide ways 18 and 19 may be formed. as here illustrated, of elongatedchannels 8| and 82 which contain blocks 83 and 84 of suitable material, having key ways 85 and 81 formed in their opposed faces, the channels and blocks being secured on the side walls of the casing by dowel screws 88 and 89, see Figure l. The slide member 14 is provided with laterally extending keys 9| and- 92 which are slidably received in the key ways 86 and 81. The guide block 83 and 94 and keysQl and; 92 are preferably formed of very hard, wear resistant material, having a low coefficient of friction. Certain steel alloys and others such as tungsten carbide or stellite are suitable. for this purpose.

The blocks 83 and84 .may be welded or brazed in the channels 8| and 8,2 and the keys 9| and 92 may be similarly secured in the body of the slide member, as shown in Figure 5.

The slide members 13 and 14 are formed with upstanding arms or bosses 96which support adjacent their upper ends transversely extending pins 91 (see Figure 5). The cam followers 16 and 11 are here in the form of roller journalled on the. pins 91 and are supported thereby in fluted recesses 98 formed in the periphery of cams 51 and 62. These. fluted recesses have a longitudinal undulation so that upon rotation of the cams alongitudinal reciprocation is imparted to the cam followers.

One of the important features of the present invention isthe manner of attachmentof the shoes l3zand M to the slide members, wherein a desired close coupled driving force is imparted to the shoes while a limited universal movement of the shoes relative to the slide members is per mitted. This construction is best illustrated in Figures 5 andfi of the drawi gs wherein it will benotedthat there is provided under the open side of the casing |2 a bottom pan 99 which completely coversthe under side of the casing but is provided with a pair of elongated openings |0| and I02, see Figures 1 and 6, to accommodate the driving connection extending from the slide members to the shoes. Any, suitable means may be used for securing the bottom pan to the casing and as here shown in Figure l the pan is formed with a plurality of up-set lugs or pins I53 which slidably fit the interior of the casing side walls. Means is provided for sealing off the openings HM and I02 so as to effectively shut out from the drive mechanism abrasives, dust, and the like. As here shown, such means includes sealer plates I04 and H16 which are carried with the shoe connection and are provided with an upstanding peripheral flan e I01, see Figures 5 and 6, containing within thefiange an O sealing ring I08 which is compressed between the plates I04 and H36 and the under side of the bottom pan 99.

The shoes |3and I 4 are of generally rectangular construction having a width completely underlying the unit as shown in Figure 5 and a combined length covering the majority of the length of the un t. 56 Figure a d are subjected to a reciprocating movement extending to and slightly beyond the opposite ends, of, the unit, so that the sanding patternafiorded completely covers and verlaps. th t nsv rse nd l n i ud al dime sions of the unit. Also, the shoes are constructed in a manner permitting the easy renewal of the sand paper or polishing cloths or the like. As will be best seen from Figures 5 to 8 of the drawings, the shoes are here composed of a plurality of superimposed plates I09, III and H2. The lowermost plate I09 is formed with upstanding flanges H3 and H4 at its opposite ends, which extend upwardly from plate I09 in horizontallyspaced relation to upstanding flanges I I 6 and I I! on plate III, so as to define channels I I8 and H9 therebetween, the plates being preferably integrally secured together as by spot welding or the like. The uppermost plate II 2 is locked to plate III by a return gripping flange provided at the upper extremities of the flanges H6 and HI. i

P A post assembly is used to connect the shoes to theslide members and also to carrywith it the sealing plates I04 and I06. This construction is best detailed in Figures 5 and 6 wherein it will benotedthat the sealing plate IE4 is provided with -a centrally arranged depending spherical boss I2I which is received in a spherical recess I22 formed in the top plate I I2 of the shoe by .a general elevation of the central portion of the plate H2 from the intermediate shoe plate I I I. A post or pin I23 extends centrally through the ball and socket connection provided by the boss IN and recess I22, and is the main connecting element of the assembly. As will; be noted, this post is provided with an enlarged head I24 underlying and fixed to the recess portion of plate H2, and extends centrally through this recess and through a centrally arranged opening I 26' in the boss I2I. The upperend I27 ofthe post extends through an opening I28 provided in an inverted cup I29, the post being held against retraction by a cross pin I 3i carried by the post end I2! and looked over the periphery of the opening I28 in the cup member. Preferably, as seen in Figures -5 and 6, a bayonet-type of connection is used for this post end so as to permit its removal when desired.

As an important feature of the present construction, resilient means is employed in the operating connection between each of the shoes and the slide member, so as to constantly urge the shoes to assume a horizontal position parallel to the slide members and to resiliently resist movement from such position. As here shown, such resilient means is in the form of compressible pads I32 carried in the inverted cup member I29 in surrounding relation to the post, I23 and maintained under pressure by an underlying supporting member I33 also surrounding the post I23 and having a spherical bossl34 fitting into the interior concavity of boss I2I. The pad I32 may be of any suitable compressible, resilient material, such as rubber or similar material. Desirablsn. the dimensions of the respective parts injthe post assembly are such as to normally place the pad I32 under some compression, thereby urging the shoe into a position parallel to the sealing plate I04 and the slide member. As above noted, however, the shoe is permitted a limited universal movement eifected by the sliding contact of the boss I2I in the recess I22 within the limits of opening I26. Such a swinging movement of the post, of course, places the pad I32 under further compression, which thereby resil-' tation the inverted cup I29, the pad I32, the supporting member I33, and the sealing plate I04, by the provision of one or more flats I36 (see Figure 3) on the post I23 engaging with flats pro-.- vided in the post-receiving openings in members I33, I32 and I29. As will be seen from Figure 5, the sealing plate I34 (applicable also to the other sealing plate, I06 and its assembly) is anchored to the slide member I4 by bolts I37 and I39 which extend through apertures in the plate It l and are threaded into slide member I4. As will be noted in comparing Figure 5 with Figure 6, the cup member I29, pad I32 and underlyingsupporting member I33 are all of rectangular form, that. is, having a greater dimension longitudinally of the machine than width-wise, and these members are contained within an elongated recess I39 in the slide member 74. In this manner, members I29, I32 and I 34 are supported by the slide member against relative rotation and they, in turn, by reason of the post flat I38 and the anchoring of the post head I24 to the shoe, prevent rotation of the shoe.

As above noted, means is provided in the present construction for quick and easy changing of the sandpaper or other sheets of abrasive or polishing material which may be used with the machine. With reference to Figures 5 to 8, it will be noted that there are provided in the channels I I8 and H9, hereinabove described in connection with the shoes, locking rollers MI and I 42. These areof elongated form, as seen in Figure 7, and of oval cross-section as viewed in Figure 6, and have a transverse dimension suiiicient, upon appropriate rotation, to bind against the adjacent side walls of the channel. These rollers are supported within the channels for rotation by underlying clip members 43 and I44, which have raised bearing portions I46 and I47 at their opposite ends for journalling reduced end portions I48 and I49 of the rollers. The latter end portions may be of rectangular or polygonal form so as to fit within a key or the like which may be used for appropriate turning of the rollers. A sheet I5I vof sandpaper, emery cloth, or buf- Iing or polishing material is supported at the under side of bottom plate I69, preferably on a suitable compressible pad I52. The latter may be of any appropriate material such as felt or the like. The opposite ends of the sheet I 5i are wrapped around the exterior of the shoe flanges H3 and II Landextended into channels H8 and H9, where upon appropriate rotation of the rollers I4II and I42-the sheet ends are clamped against the shoe flanges i I6 and I I1. Preferably, flanges. H3 and I I4.extend inwardly as shown in Figure 6, so as to overhang the rollers MI. and I42 to thereby assist in retaining these rollers in the channels. The rotation of the rollers MI and I 42 to clamp the ends of the sheet [M as above described also tends to draw the sheet tightly around the bottom of the shoe, as noted.

Means is also provided for detachably secure ing the shoes I3 and I4 to their respective mountings so as to permit the renewal of the shoes or change of the type or size of the shoes. As above described,the flanges H6 and H1 of the shoe plate I I I are turned inwardly at their upper end so as to overlie the side edges of plate H2. In this manner, flanges II 6 and I I I form side channels for slidably receiving the opposite edges of plate H2. A detent means as illustrated in Figures 3, 6 and 8 is used for holding the shoe plate III in proper position upon the carrying plate H2. As illustrated, an elongated, flat spring 7' member I55 issecured at one end, as by rivet I53, to the upper side of plate I I2, across the forward extremity of this plate. The opposite end I50 of the spring member I55 is extended trans versely across to the opposite side of plate II2, where it is manually engageable for elevation against the resilient resistance of the spring member to deflection. Carried centrally of thespring member I55 isa detent button I54 which extends through a registering opening I56 in plate H2 and into an aligned opening. I51 extending through plates I09 and III. To disen gage the-shoe from the carrying plate name outer end I50 of the spring member is'raised so as to elevate the detent-button I54 from its en-' gageme'nt in opening I51, after which the shoe may be slid transversely away from the side edges of plate I12. To apply the shoe, the side shoe channels provided by flanges H6 and H1 are aligned with the opposite side edges of plate H2 and the shoe slid transversely upon the plate until the detent button I54 snapsinto the shoe plate opening I51, which looks the shoe in posi' tion.

As will be noted from the foregoing, the machine is so designed as to fall entirely within a vertical projection of the outer limits of its sanding operation, and consequently the machine can be worked into corners or any space which will contain it. In other'words, a full and complete sanding pattern completely underlies the machine. If desired, a bumper strip I58 of rubber or the like may be provided around the base of the casing forfacilitating movement of the machine into corners and against walls, etc. It will also be noted that the drive mechanism above de scribed provides an out-of-phase movement of the shoes I3 and I4, so that these shoes are always moved toward or away from each other. In'othei' words, while shoe I3 is moving to the left as viewed in Figure 1, shoe I4 will move to the right, and contrawise, when shoe I3 moves to the right shoe I4 moves to the left. In this manner, the reacting forces from the shoes to the machine are always opposed and substantially equalized, thereby permitting easy handling and manipulation of the machine without tendency. of the machine to walk" on the surface being worked. The feature of dynamic balance is also generally carried through in the drive and driven parts by reason of the general symmetry of the driven parts about the drive shaft 38. The drive mechanism here used also affords the use and appli cation of relatively high horse power in a machine of limited size. In this connection'it will be noted that the main drive forces of themachine and'all stresses resulting from either re-' ciprocating or shock strains are contained entirely. within the gear casingassembly, and its cover plate 23,. which may be ruggedly constructed with ample factor of safety to withstand these forces. Also, provision is made for complete lubrication of the gear train including: the

worm 41 and pinions 48 and 49, in that the gear chamber 39 is completelysealed and is desirably filled with a suitable lubricant. A drain plug I59 is preferably provided in the bottom of the gear surface being worked to a plane surface.

8 chambe'r'for periodic removal of the lubricant; It will now be clear that the machine of the present invention is ruggedly constructed for powerful, high-speed operation and for long con tinned usage with minimum attention or repair. At-the same time, the machine may bereadily handled over all types and contours of surfaces, the swivel action of the shoes providing an autoinatic accommodation to other than fiat surfaces and allowing the operator to rock the body of the machine over to one side or the other to clear side obstructions while leaving the shoe flaton the surface. While such universal mounting of the shoes is provided, as above described, the driving force is applied to the shoes very close to the sanding surface, so that maximum utilization of the applied force is obtained without undue stress on any of the connecting parts. Also, the resistance to swiveling action of the shoe is controlled by the resilient pads in the post assembly above described, and if desired pads of difierent stiffness may be used with the machine for obtaining desired sanding characteristics. For'example, stiffer blocks tend to sand out the Pads of diiferent characteristics may be readily in;- serted by disassembling the shoe connection as above described.

We claim:

A sanding machine comprising, a casing, .power driven reciprocatin means in said casing, a sealing plate slidably mounted on the under side of said casing for reciprocation, a sanding shoe, said plate and shoe being formed with interfitting ball-and-socket portions supporting limited universal action, a post member secured to said shoe and extending through said ball-and-socket por tions and connected to said first means forrecipr'ocation of said plate and shoe, and a resilient pad carried by said post member and resiliently resisting displacement of said shoe away froma position substantially parallel to saidplate.

ALLAN B. WALKER. HARRY J.- RIDDLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

